Effects of caffeinated chewing gum on prolonged repeated-sprint performance in normobaric hypoxia

This study aimed to investigate the effects of caffeinated chewing gum on performance during a prolonged intermittent-sprint test (IST) under normobaric hypoxia.

Ten team-sport athletes (six men and four women) participated in a double-blind, randomized crossover trial with a counterbalanced treatment order, chewing either caffeinated gum (6 mg/kg) or placebo gum on two separate occasions, 7 days washout period. After chewing for 10 min, participants performed an IST protocol in hypoxia (inspired oxygen fraction: 16.5 ± 0.2%, ~2,000 m). The IST consisted of two 40-min halves separated by a 15-min halftime recovery, each comprising twenty 2-min blocks with an 8-s all-out sprint, 100 s of active recovery at 35% of peak oxygen uptake, and 12 s of passive rest. Total work done, power output, muscle and cerebral oxygenation were recorded.

Total work done was significantly greater with caffeinated gum, increasing by 4.4% in the first half [mean difference = 6 kJ, 95% CI (2.71, 10.08)] and a 2.9% increase in the second half [mean difference = 4 kJ, 95% CI (1.18, 6.57)] compared to placebo (all p < 0.05). Caffeinated gum also significantly increased both peak and mean power output (all p < 0.05). Cerebral total hemoglobin and oxyhemoglobin were higher in both halves with caffeinated gum, while muscle deoxyhemoglobin and reoxygenation capacity were significantly higher in the first half compared to placebo (all p < 0.05).

Caffeinated chewing gum (6 mg/kg) enhances prolonged repeated-sprint performance under normobaric hypoxia, accompanied by increased cerebral oxygenation and muscle reoxygenation capacity.